This application seeks continued support for studies of synthetic molecular assemblies. The assemblies are reversibly formed dimers of self-complementary molecules and are held together through weak intermolecular forces. The assemblies become closed-shell structures that act to encapsulate smaller molecules. The syntheses of these capsules of various sizes, shapes and solubilities are proposed and the behavior of their assemblies are to be determined. The specific issues to be addressed involve the effects of functional groups on guest binding; dynamic processes such as rates into and out of the capsules and molecular motions within the capsule by the guest; the use of the capsules as reaction chambers to catalyze rearrangements; the capacities of the capsules as asymmetric microenvironments, and their use as sensors or signaling devices. Many of the phenomena observed with these synthetic systems mimic those of naturally occurring assemblies such as allosteric enzymes and viral coat proteins. It is hoped that the rules governing the assembly process and the phenomena such as selection, transport and catalysis which owe their existence to the assembly, can be deciphered with the synthetic systems.